Clemson University TigerPrints Publications Glenn Department of Civil Engineering 1-2017 Role of Ground Glass Fiber as a Pozzolan in Portland Cement Concrete Hassan Rashidian-Dezfouli Clemson University Prasad Rao Rangaraju Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/civileng_pubs Part of the Civil Engineering Commons Recommended Citation Please use the publisher's recommended citation. http://trrjournalonline.trb.org/doi/10.3141/2629-06 This Article is brought to you for free and open access by the Glenn Department of Civil Engineering at TigerPrints. It has been accepted for inclusion in Publications by an authorized administrator of TigerPrints. For more information, please contact [email protected]. Initial Submission for Review and Publication – 2017 TRB Annual Meeting, Washington DC, January 8-12, 2017 Role of Ground Glass Fiber as A SCM in Improving Selected Properties of Portland Cement Concrete Hassan Rashidian-Dezfouli Graduate Student of Glenn Department of Civil Engineering, Clemson University, Clemson, SC-29631; Email: [email protected] Prasad Rao Rangaraju (Corresponding author) Professor of Glenn Department of Civil Engineering, Clemson University Clemson University SC-29631 Phone: +1-864-656-1241; Email: [email protected] Word count: 4975 words text (without references) + 9 tables/figures x 250 words (each) = 7,225 words Submission Date – August 1, 2016 1 Abstract Millions of tons of fiber glass are produced annually for a variety of applications every year. Due to stringent quality requirements and due to operational characteristics of the manufacturing plants, a significant quantity of fiber glass that does not meet required specifications of the industry ends up as waste and is disposed in landfills. In this study the use of ground glass fiber (GGF), discarded from the plants as an off-spec product, as a supplementary cementitious material (SCM) was investigated at different replacement levels (10, 20 and 30% by mass) of portland cement in paste, mortar and concrete mixtures. Mechanical and durability properties of the mixtures were compared with two control mixtures: a mixture with 100% portland cement and a mixture having 25% class F fly ash as a cement replacement material. It was observed in these studies that even though replacement of portland cement with GGF does not lead to any significant changes in the mechanical behavior of hardened concrete, significant improvements in the durability properties were observed at replacement levels up to as high as 20%. Use of GGF was found to significantly improve the resistance of mortar mixtures against alkali-silica reaction and sulfate attack. In addition, the use of GGF as an SCM significantly reduced the chloride ion permeability of concrete. Results of this study showed that using GGF as an SCM can result in a better durability performance compared to a mixture having similar level of class F fly ash. 2 1 INTRODUCTION Utilization of ground glass powder, typically obtained from processing of recycled glass containers made of soda-lime glass, as an SCM has been the subject of many studies (1-4). Due to the high amount of alkali present in these glass powders, susceptibility of concrete mixtures containing glass-derived pozzolans to Alkali-Silica Reaction (ASR) has been always a big concern. On the other hand, ground glass fiber (GGF), a pozzolan derived from finely grinding fiber glass (commonly referred to as E-glass) that has very low alkali content. Due to its chemical composition, GGF can potentially serve as a valuable pozzolan without the negative effects often associated with the use of high-alkali glass powders such as soda-lime glass, particularly in reducing the risk of ASR in the concrete mixtures. Presence of reactive silica is essential for any supplementary cementitious material (SCM) to cause the pozzolanic reaction. Although like other SCMs, GGF has high enough combined silica, iron and aluminum oxide (S+A+F) content (i.e. > 50%) and can serve as a good pozzolan, unlike other SCMs such as fly ash, GGF is an engineered material which is produced in a controlled environment. This results in a uniform chemical composition of the material which lends itself to a consistent quality SCM for use in concrete. Utilization of GGF as an SCM in concrete construction is a relatively new concept and unlike the conventional SCMs like fly ash, slag, meta-kaolin and silica fume, which are known to be used for several decades, the first use of this material as pozzolan was patented in 2004 by Hemmings et al (5). According to a report by the US Department of Energy in 2005, the total amount of waste glass fiber in United States that ends up in landfills was about 250,000 tons per year, which can be reclaimed for beneficial uses. This amount can be further increased to 500,000 tons/year if the waste streams from the users of glass fibers are also considered (6). Past studies on the utilization of waste glass fiber as a SCM, have shown the advantages of using this material in improving some fresh and hardened properties of mortar and concrete mixtures. Chen et al. (7), investigated the utilization of E-glass particles in concrete mixtures. It was seen that the replacement of E-glass as cementitious material, up to 40% by mass of the cement showed pozzolanic reactivity. Furthermore, it was observed that the addition of E-glass as a cement replacement improved durability characteristics of concrete such as resistance against sulfate attack and chloride penetration. Hossein et al (8), studied the fresh and hardened properties of the concrete mixture containing glass fiber particles. It was reported that utilization of this material as a cement replacement increased the workability of the fresh concrete mixtures (higher slump), increased the plastic shrinkage and also reduced chloride ion permeability. A few studies have been performed on the hydration mechanism of the mixtures having glass fiber as a cement replacement. A comprehensive study on the pozzolanic properties of milled glass fiber was performed by Neithalath et al. (9). It was reported that although the glass fiber powder did not show any cementitious properties, it had a significant pozzolanic effect. In addition, it was seen that addition of glass fiber (as cement a replacement) was very beneficial in reducing the calcium hydroxide level. In another study, Kamali and Gharemaninezhad (10) investigated the hydration and microstructure of cement pastes modified with glass fiber powder. It was found that addition of fiber-glass powder as cement replacement, improved the early hydration of the cement 3 and also showed pozzolanic reactivity at later ages (i.e. 91 days). Furthermore, it was observed that the addition of fiber-glass reduced the porosity. This paper presents selected findings from a comprehensive study conducted to evaluate the material characteristics of a ground glass fiber produced from E-glass and its role in affecting a range of fresh and hardened properties of pastes, mortars and concrete. Findings from the material characterization of GGF and its effects on fundamental material and selected mechanical properties of cementitious matrices are published elsewhere (11). The focus of this paper is to report findings from studies conducted to evaluate the impact of a specific GGF of defined fineness on selected mechanical and durability properties of mortars and concrete mixtures. To evaluate the mechanical properties, concrete specimens were tested for their compressive strength, splitting tensile strength, and modulus of elasticity. In addition, durability properties of the mixtures containing GGF were evaluated by conducting alkali-silica reaction, sulfate attack and, rapid chloride penetration test (RCPT). Furthermore, to assess the pozzolanic behavior of the GGF, strength activity index (SAI), and thermo gravimetric analysis (TGA) were performed on mixtures containing various level of GGF. 2 EXPRIMENTAL PROGRAM Materials: Following materials were used in this study: 2.1.1 Cement In this study, a Type I/II (ASTM C 150) ordinary portland cement (OPC) with a specific gravity of 3.15 and an average particle size of 17 microns was used. The chemical composition of the portland cement and its selected physical properties are presented in Table 1. 2.1.2 Ground Glass Fiber The Ground Glass Fiber (GGF) used in this study was a fine white powder that was prepared by milling the off-spec glass fiber in a ball mill to a fine powder with an average particle size of 4 microns. The scanning electron microscope (SEM) observation showed that the GGF particles were angular with a smooth surface texture. The chemical composition of the GGF and its selected physical properties are presented in Table 1. 2.1.3 Fly Ash A class F fly ash (ASTM C618) with a specific gravity of 2.25 and an average particle size of 28 microns was used as an SCM. The chemical composition of the fly ash and its selected physical properties are presented in Table 1. 2.1.4 Fine Aggregate (Siliceous Sand) A non-reactive siliceous river sand meeting ASTM C33 gradation requirements with a fineness modulus of 2.60, absorption of 0.30% with an oven-dry specific gravity of 2.67 was used in this study. 4 TABLE 1. Chemical Composition and Physical Properties of the Cementitious Materials Chemical composition/Physical properties Cement (%) GGF (%) Fly ash (%) 19.9 47.7 50.7 62.3 19.6 3.3 2 4.8 10.4 25.1 3.1 0.3 12.5 23 2.7 2.3 1.1 23 0.38 0.70 2.0 Chemical composition Chemical SO3 3.23 0.02 0.70 2eq Specific Gravity 3.15 2.60 2.25 Amount Passing #325 Sieve (%) 98% 96% 76% Blaine's fineness ( / ) 4720 10200 6040 Physical properties Loss On Ignition (LOI)2 2.6% 1.0% 2.3% 2.1.5 Coarse Aggregate: In concrete mixtures, a #57 (ASTM C33) granitic aggregate with the specific gravity of 2.65 and absorption of 1% was used.